I've been experimenting some with do it yourself microwave popcorn, and some trouble getting the 'burn time' right has led me to a question that I can't find a good, definitive answer to.  What is the scientific explanation for the mechanism for how popcorn burns?  I'm not looking for "Because it gets too hot", but what gets too hot, how does it actually get that way?  Microwaves don't just heat everything up (like a stove does), so it's not as straightforward as that.  You can put many foods inside of a microwave and massively overcook them without burning.  So what's special about popcorn that causes it to burn?  I would prefer either a detailed chemistry/physics answer, or  a reliable, science-based source.  From looking around online, there are lots of semi-reliable opinions on this, none of which agree with each other.  For example, this very old Chicago Tribune article on Popcorn seems to say that it's a problem of "finding" the kernels.  Really?  Others claim it is the kernel overheating, or the bag overheating, or the oil overheating (yet no-oil still burns, though that may contain some oil from the corn itself I suppose), or gnomes lighting them on fire with matches (Well, no, but it's about as reliable as anything else I've found).  And related to this, what control do I have over this other than time.  On a stove, I can reduce the heat; for example, if I'm cooking on the stove with butter, if I cook at '3' I can cook almost all day without burning my butter, while at '4' it browns pretty quickly; so I can choose whichever setting based on that.  What in a microwave would be similar (in allowing me to cook the kernels more thoroughly - not just take longer - without risking burning).  What ingredients or microwave settings can I control? 
Graphics and quoted text from: Whole Grains Council Grains, by definition, have 3 major parts: the germ, the endosperm, and the bran.  Whole grains are those that have all of the parts of the natural seed, or kernel (not including an exterior husk that is generally inedible). To be called "Whole Grain" the product must still have all of the bran, endosperm and germ that it had when it was in the field, although it can milled, ground, cracked, natural, whatever...as long as it still has all of its parts.  If a food label states that the package contains whole grain, the "whole grain" part of the food inside the package is required to have the same proportions of bran, germ, and endosperm as the harvested kernel does before it is processed. Refining normally removes the bran and the germ, leaving only the endosperm. Without the bran and germ, about 25% of a grain’s protein is lost, along with at least seventeen key nutrients. Processors add back some vitamins and minerals to enrich refined grains, so refined products still contribute valuable nutrients.  This graphic shows what's lost when wheat is refined, and what's added back when it's "enriched":  Durum is just a variety of wheat. Unless it specifically says "whole wheat" or "whole grain", you can assume that it is refined. 