I've noticed that if the last little tidbit of baking experience is earned off of a burnt item, I don't get the message about going up a level. It's happened to me both times I've leveled up. xD (I'll try to get a screenshot if it happens again!)

I think you stop getting experience from it after a certain level. I noticed I didn't get any when I'm sure it was said that you could still get at least one point, but I am at a fairly high level now. Maybe they should make that more clear?

Ive had this issue before as well but I am only level 4. I was also wondering if it was possible to still burn your food even if you came back in time to pick it up? Or is being about 15 seconds late enough of a reason for her to burn my food?