"I don't know if Cassadee knows this, but she was actually my first ever show outside of Nashville," the country singer-songwriter, 31, tells PEOPLE. "I was opening up for her at Bogart's in Cincinnati."
"Really?" Pope, 33, asks aloud. "That's so cool."
Perhaps even cooler is the fact that Hummon has also long wanted to write alongside Pope, going as far as holding certain song titles and ideas for her until the moment that they could finally collaborate.
"Even this [writing session] got moved three or four times," chuckles Hummon, the son of noted musician Marcus Hummon. "But this time, I was determined to make it work."
John Shearer; Logen Christopher Cassadee Pope and Levi Hummon
It certainly worked. The pair's new song "RSVP" serves up a sonic adventure of sorts for the two artists, who have each swayed back and forth between pop and country. The sounds combine quite nicely on the song, which Hummon had held in his back pocket for Pope for a while — under its original title "After Party."
"It wasn't really a country song, it wasn't really a pop song. It wasn't really anything, but just kind of a story of being alone after the party and wishing that the one person you wanted there was there," remembers Hummon of creating "RSVP."
He continues, "The whole time, Cassadee kept bringing up the whole 'Ross and Rachel' [from Friends] thing, where they both want to see each other, but it never comes into fruition. That's what Cassadee really contributed to the song. I mean, she elevated the song to a whole other level."
Certainly, Pope has done this many times before, both in the writing room and in the recording studio, collaborating in the past with country music hitmakers including Chris Young and Little Big Town's Karen Fairchild.
Reservoir Cassadee Pope and Levi Hummon
"I love everything I've collaborated on with anybody else before," shares the Voice alum. "Often, I come in after the song's been written, and I try and add my spin to it, but this is really the first collaboration that I got to really creatively contribute to and be another writer in the room for."
For that reason, Pope says she feels truly connected to "RSVP."
"The subject matter is something that gets covered constantly in movies and TV shows, but I've never really heard it in a song like this," says Pope. "So, I really was proud that we stayed on track and really got that feeling across in the end."
Nevertheless, the lyrics of "RSVP do leave some creative strings untied, which is another thing that the two artists adore about it. "We don't want to overexplain in the song," says Pope.
"Basically, all he wanted was her," adds Hummon, "and she never showed up."
But for "RSVP," Pope did show up, allowing Hummon to finally get to collaborate with the artist that has intrigued him for so many years.
"I'm not only a fan of her voice, but I'm also a fan of pushing the boundaries with what is country music or what is music and who we are as artists," remarks Hummon, who collaborated last year with Walker Hayes on the viral "Paying for It."
"I knew that Cassadee is one of those people that could really help me establish that with just purely her voice," he adds.
"From a really young age, I learned how to sing with people," recalls Pope. "There are times where I step out, and I sing a bit differently when it's solo, and then you sing a little different when you sing with somebody. That's just part of collaborating with somebody."
She pauses for a moment.
"I think that's what really sets people apart," she says quietly. "I love when people can collaborate and blend with somebody else rather than it being this screaming contest. It can be good, but it's kind of intense and annoying sounding sometimes."
"RSVP" also allows Pope to continue her musical journey in a bit of a different direction — once again.
"I'm moving away from the country space and going more into pop rock where I came from initially," explains Pope, whose career began in the band Hey Monday. "I'm glad that ['RSVP'] kind of straddles those lines. It's a great kind of bridge for me between what I did before and where I'm headed with my next solo project."