One I can recall is Topolino Capostazione. I read it for the first time when I was 8 and I understood almost nothing past the first few pages. I read it again when I was 10 and I understood all of it! I was impressed at how different my mental capabilities were compared to 2 years earlier.
There are some comics of which I only remembered a few panels... then when I read them again, I realized that I didn't find the story very engaging and that was probably why I forgot it.
Including a story where fairy tale characters come to the real world through a fax machine and one where robots turn iron junk into edible cakes.
I could also mention a story where Donald turned pencil leads into diamonds by using some kind of fruit mixer made by Gyro... literally making truckloads of diamond pencil leads and selling them. I totally forgot the outcome. Turns out, the huge amount would make the price of diamond go down.
A story with a similar outcome: Scrooge finds a lost tribe in the jungle that owns a lot of gold, but is forced to run away. HDL then tell him that if he got that gold, the huge amount would have made the price fall down. However, as a kid, I didn't understand that last part and it really didn't get in my head.
--- Gaucelm de Villaret firstname.lastname@example.org gaucelm.blogspot.fr