Boom Clap - Aeroplane Remix

This song features on the soundtrack of the romantic comedy-drama movie The Fault in Our Stars. "The scene that ['Boom Clap'] is in is an uplifting moment in the film," XCX explained to Billboard magazine. "And while the song itself is very euphoric and enthusiastic about romance… it's about wanting to fall in love, but there's this hint of sadness in that, which I like."

Charli and Patrick Berger wrote this song in Stockholm. She explained the inspiration to Entertainment Weekly: "We had been listening to loads of French yé-yé pop and the Flying Lizards and Bow Wow Wow, and we were saying how all those songs have dumb, hooky, shouty choruses. They're all sort of childlike. So we wanted to make a song like that.

The song celebrates epic love. "Being totally immersed in passion and feeling really safe and really alone with that person," Charli explained to MTV UK. "Although I always hear a tinge of sadness in it, that song has quite an acute feeling."