First option is to leave the pan in cold water over night. This, somehow, breaks down the proteins that might be left in any burnt residue. I learnt this many years ago when I worked in the kitchen of a small hotel. Manys a time poridge would end up being burnt onto the bottom of a saucepan and I'd break into a sweat cleaning it only to given this tip by the owner and surprisingly it works! Not quite sure how well it will work on something you might have effectively destroyed by even burning the water in it?