Beau is Afraid was the last one I recall. I think it was mostly the latter half of the movie where I started to get a bit confused and needed the ending explained to me.
What movies made you look up some kind of explanation afterwards? I feel like I have done it several times in the past for more surreal movies but can’t think of any other examples.
It can also be a TV show.
For Interstellar, I think it’s either you get it or you don’t. I got the idea pretty well, aside from the physics and stuff behind it. I talked with some people who couldn’t understand it and tried to explain it but it still left them confused.