Igneous Heterodyne was an ancestor (or at least relative) of Agatha's who at some time in the past, an event which was witnessed by both Castle Heterodyne and Airman Higgs. From the context in which he is mentioned, it could be assumed that this explosion was the result of experiments involving drinking water from the The Dyne without following up with a procedure to deal with the water's volatile energies.
How to not explode Edit
Asby Agatha it is possible to stop the process before it makes you explode if you transfer the excess energy to another person or persons. Done properly, this will not only prevent said explosion, but leave all involved with a pleasant charge of almost entirely non-deadly energy that can be readily harnessed to any number of uses.