Most people have heard of nitroglycerin, either as a heart medication or an explosive. It's mind boggling that one compound could blow your face off or save your life, but it can. Discovered by Ascanio Sobrero in 1847 the molecular structure of nitro is the key to it's dual purpose. Not surprisingly, since he had just discovered the combination, he wasn't entirely familiar with how volatile it was and was badly injured in his lab when there was an explosion while he was working with it.
For combustion to happen, there must be fuel and oxidation. In nitroglycerin this happens in the nitrate molecules which are both fuel and oxidizing agents. A combustion will reaction happen just within those molecules alone. This makes them very unstable.
Famous physicist Alfred Nobel stabilized a formulation of nitroglycerin that could be used in a more controlled way as an explosive. It wasn't until the 20th century, with research into nitrate combinations for chest pain, that it was discovered that the body converts nitroglycerin to nitrous oxide (laughing gas anyone?) which relaxes blood vessels, easing chest pain and keeping the heart from having to work so hard. It's both a deadly substance and a life-saving medication. All because of chemistry.