Back when it was acceptable to work with RH5 wheels, a loud pop while inflating the tire was a sign that the wheel halves had seated properly. It usually happened somewhere around 30 PSI as the tire, tube, inner liner, and wheel assumed the proper fit to each other. That was also the most dangerous point, where an improperly assembled wheel was most likely to have a catastrophic failure. ALWAYS use an inflation safety cage when dealing with any multi-piece wheel, but if you ignore common sense and all the warnings about RH5's, definitely use a cage, and a long "chicken hose" with a clip-on chuck and an on/off valve in it and hide behind something sturdy while inflating the tire.
Jerry
