Here's an introduction to avant-garde music. No lounge or pop music, but worth listening to.
Open Culture shares this terrific playlist on Spotify. Unfortunately I can't embed it so you will have to follow this link, title of the playlist: A Young Person's Guide to the Avant-Garde. It contains tracks from Erik Satie, Kurt Schwitters, Jean Cocteau, John Cage, Stockhausen, Varese et cetera.