While I know that steam helps loosen everything inside the microwave, I was a bit skeptical of this pin after reading the comments. However, my microwave desperately needed cleaning for the Thanksgiving holiday, so I decided to give it a try. My end result wasn't too bad.
Here's the original blog post that I pinned on Pinterest--http://lifehacker.com/323232/steam+clean-the-microwave-with-vinegar . I started out by filling my bowl with half water and half white vinegar. I love the smell of white vinegar, so I wasn't worried about the comments that mentioned the smell. I was worried about the comments that said their bowl exploded, so I started out at 2 minutes and then added one minute and then another minute for 4 minutes total.
I will say that even after 4 minutes on high, I still had to scrub a bit in spots, and the cleaning wasn't as easy as I had hoped. It was definitely easier than before, and my microwave looks clean. Let me know how this works out for you if you try it.