When I made spaghetti sauce last week I cooked it in my big Le Creuset French oven (which I got at almost half-price so don't judge, yo!) But when I went to pour the sauce out I discovered that some of it had burned on the bottom. It was horrible! I scrubbed what I could off and let it soak with dish soap overnight but to no avail. There was still a thick black layer of crud on the pot.
Then I did a search online and found that some people recommended mixing dishwasher detergent and water in the pot (you want to stir it so the powder dissolves) and then bringing it to a boil, covering it, and letting it sit overnight.
I decided to try it out. It was amazing! The heavy burnt-on crud started lifting off the pot as soon as the water came to a boil; it didn't even have to sit overnight.
So if you ever find yourself in a similar situation I would definitely give it a try.