After food has splattered in the microwave, it can be hard to clean up. Just heat 1/4 cup of vinegar with 1 cup of water in a cup or bowl in the microwave. This will loosen splattered on food and deodorize. I let it sit for about 3 to 5 minutes letting the steam loosen the splatters but also allows for the water to cool down. I then take the vinegar/water mixture and moisten a rag or sponge to wipe the inside down.
Also if you have had burnt popcorn smell in the microwave doing, microwaving the same mixture will remove the odor.