Back in the good old days I was one of the few lucky scientists who got to work at was then known as the AF Rocket Propulsion Lab (AFRPL) . It was a great place to experiment with different types of rocket systems, including liquid, solid, plasma, solar and some other exotic designs. At RPL most rocket tests were static, meaning they were held in place as they fire.
The following sequence of images was taken by a colleague ( who's name escapes me at the moment ) of a test firing of a new solid rocket motor design.
As you will see things didn't go as planned. Fortunately, no one was injured.