If you keep a damp rag handy and wipe it up as you go, it won't have a chance to harden on. If you can't do that, at least keep it wet.
Someone else suggested spreading tinfoil over the top of the stove before you start. When you're done, toss it in the trash.
I never get wort on the stovetop, but I always end up with a sticky floor by the time I'm done since I pour and splash the wort after cooling. I have a big roll of leftover rosin paper from moving in and might throw a couple sheets of that down over the kitchen floor to serve the same purpose as the foil on the stove.