Mystery gunk on crock pot. HELP!?

Ok, so here's the deal. Recently, my mom made some chicken in her ceramic crock pot. She'd done this before, and this has never happened before. So, I do all the dishes in our house, and when I get the crock pot, there's the usual gunk on it, as well as a beige plaster on the inside. So I scrub it with a brush, soap, and all the elbow grease I can muster, and it looks clean. I put it in the dishwasher, and when it's done I empty it. The crock pot still has the plaster stuff on the inside. So I scrub it again and I discover that the gunk seems to disappear when water touches it (this happens often with our dishes). So I scrub it and run it through the dishwasher multiple times, scrubbing it between each wash. It just came out of the dishwasher for the third time, and it looks the same as it did when it was first dirty. I don't know what this is, i've tried using a brush and soapy water, my fingernails (such as they are) and soapy water, a brush with soap, letting soapy water sit in it, i even put extra detergent in the dishwasher this last time and it's still dirty! this gunk is spawn of the devil! how do I get rid of it?