I think a lot of people quickly forget that Azar is quite the skilled inventor. While his expertise lies within the fantasy realm of steampunk-style technology, he still loves to tinker and create whatever new ideas come into his mind. It's primarily through trial and error that his greatest successes have come about, and about 50% of his errors end up in a situation much like this. Good thing dragons are durable!
There's no telling what fascinating new device he was working on, as there aren't many parts left after the explosion to really tell what it could have been. But knowing Azar and his inventor ways, it could have been anything from a new, experimental kind of power source to a mechanized way to flip pancakes at just the right moment. Hopefully he'll get it right on the next try!

Art by the amazing