I noticed a similar phenomenon in my days at school. When solving problems on my own I was reasonably successful, but in class when I found out - or someone me

I noticed a similar phenomenon in my days at school. When solving problems on my own I was reasonably successful, but in class when I found out - or someone mentioned - that a particular problem was extremely difficult and/or no one had managed to do, I do exceptionally well in it. As for an explanation to this, I have no idea. It maybe has something to do with the fact that if I fail at the difficult problem then a lot of people have seen me fail at it, but that's just guesswork.