To get rid of the awful lingering smell of burnt microwave popcorn, fill a large microwave-safe bowl with one cup of water and sprinkle your favorite spice like cinnamon or add several drops of vanilla or lemon extract. Bring to a boil. Let it sit inside for 10 to 15 minutes to cool down. Simply wipe the walls down with paper towels. Leave the door open to further air it out.
I use mix of bottled lemon juice and water in a pyrex measuring cup. Put it in the the oven and run for about a minute. Depending on the power of your oven it should strike a boil by that time. I use this concoction for everything from burnt popcorn to general clean up. The help line at the manufacturer of my first microwave told me to do this at least 15 years ago. It won't leave a residual odor but gets ride of "ugly" odors.
This is a wonderful idea and it will also deodorize your kitchen as well. Another great thing to do would be to do the same thing on your stove in a pan. As a child my father used to use orange peels and water, bring them to a boil and allow the smell to enter the entire house. I am sure any spices and or fruit throw aways would work the same. Word of warning don't allow your pan to boil dry.