Actually it can, mine is like that too.
Easiest way to clean it is to burn it out. If you have a kettle, fire that sucker up with a good pile of lump. When it's all burning, set the water bowl on it. Yes, right on the coals. It'll burn off the gunk inside to the point that it can be basically wiped out like ashes.
I never foil mine anymore. I use it naked (the water pan, not me!) and I just bring it in and wash it out after every cook. It cleans easily.
That has happened to me when my water pan has boiled dry. I just put hot water back in and let it reach boiling. It's amazing what will lift off after an hour or so. I do the same with cast as well. What does not lift off will soften and with a little elbow grease you should be able to get it off, after all it is only stuck to porcelain.