I've been slowing making my way through the kitchen and yesterday I cleaned the microwave. The burned-on stains are the tough to remove but with a trick up my sleeve the task was much easier. Fill a bowl with 1/2 cup of vinegar and 1/2 cup of water. Bring the mixture to a boil for about 30 seconds in the microwave and then stop the heating mode. Let it stand for several minutes. The vapor will help loosen up the stains and make them much easier to remove.