My high-school chemistry teacher told us that elemental sodium is extremely volitile, that it will explode on contact with water. (She also heated the classroom on cold days by lighting 30+ bunsen burners, and she good-naturedly answered the compulsory "Does it explode?" question before every demonstration.)
This guy decided that he hadn't been given sufficient proof of the sodium-water phenomenon. (Great pictures, and video if you want it.)
theodoregray.com/PeriodicTable/...
He's also responsible for the Periodic Table Table:
theodoregray.com/PeriodicTable/...
