Brown peeling stuff behind wallpaper!?

I'm painting my living room and there are about 4 layers of old wallpaper and underneath it all there is some sort of brown colored wall. I don't think it's drywall. I have no idea what it is. I sprayed some water on the wallpaper to help peel it off, and when the brown stuff got wet it started peeling. I have no idea what to do. It's sort of like trying to get a barcode sticker off of a bowl or a plate or something like that...it just keeps coming off in little shreds. I want to keep scraping it off to see if it will eventually stop peeling, but I'm afraid that I will mess it up somehow. What should I do!?!? I'm so puzzled!