I'm talking about hearing something that makes you go "wow, what is going on here?" not being able to appreciate it right of perhaps, but still you know instantly something is going in there that requires you to listen to it again.
Examples for myself are the Master Musicians of Jajouka whom I've heard for the first time this year. My discovery of the wonderful world of freejazz some years ago. Hearing Indian raga music for the first time during a Remember Shakti gig. Mike Pathos - People is an album that disrupted my ears well and hard.