Clean a pot that had jam in it and stuck & burned to the bottom of the pot?
Add lots of water, let it soak several hours, use a brush to remove what comes out easily. Repeat. When you get to the very end, you are likely to have to use a scouring pad or something, some elbow grease, and something like Bar Keeper's Friend. Fortunately, sugar, even when burned, will generally dissolve in water, so as bad as it looks, it is probably less work than you think if you can stand to soak the pot and work at it a little each day for a few days.
Sprinkle powdered dishwasher detergent in the pan, add water, and boil. It will loosen the stuck on material.
Kathy has the answer. After boiling add lid to also steam it.
Pour a can of room temperature Coca Cola leave it overnight and that should take care of it.