It seems that there are limitless ways that sugar can kill people. Not content to limit itself to slow murder due to caloric intake, it has branched out into sudden, violent death. Find out how and why sugar can explode.
Sugar burns. This fact has caused pain to anyone who has ruined a cake by leaving it in the oven, or had to pretend to enjoy a blackened smore, but pastry kitchens generally don't blow up like meth labs, and it's legal to bring cupcakes on airplanes. What is it about powder that makes sugar go from ruined meal to kaboom?
Powder is more likely to flame sudden and fast than pastry. Fire needs oxygen, and small things are more likely to be able to strike a balance between giving a flame both fuel and air. Most people who have started fires – under whatever circumstancs, Io9 doesn't judge – know that they need kindling to start out. Grains of sugar are more likely to catch fire than large blocks of wood.
Location is also a factor in sugar explosions. The fact that sugar grains burn so fast stops some explosions from happening. There's not a lot of fuel in them, and in order for a big explosion to get going, the grains have to be spaced just right.
Up until the nineteenth, fireships were sometimes used in naval battles. Fireships were either old or cheap ships that were loaded up with fuel, set on fire, and pushed toward enemy vessels in the hopes of setting those vessels on fire. Those flaming ships would then set more ships on fire until, with any luck, there was no more enemy. The fuel for the fireships had to be judged just right. If the ship burned too fast, it would burn out and sink before reaching the enemy.
The sugar grains are much like that. They have to be in a position where they can reach the next set of grains and set them on fire before they flame out. That set has to reach the next, and the next, and the next in order to keep the explosion going. That makes it unlikely in domestic situations. In food manufacturing plants, it is a real danger. When sugar has caused explosions, it's been in refineries, where sugar coated the walls and surfaces, and powdered sugar was suspended in the air.
It's not just sugar that explodes. Flour is also made up of carbohydrates – lots of sugar molecules stuck together. It, too, can explode the same way sugar does. I assume cocoa powder can too. Most organic materials burn. Probably baking soda.
Now I just need to find a way to make eggs, butter, and vanilla explode, and I'll have the ultimate weapon, combustible cake, and the world will be mine.