Why did my inner tube pop or explode?
Although the inner tube holds the air pressure, the tire itself is what actually contains the tube so it holds the proper shape and remains intact. A tube is like a balloon -- it will keep expanding until it pops if not incased in a tire.
The only way that the tube can physically explode is if the tube material is outside of the rim/tire and gets stretched beyond its means (when inflating your tire, do not exceed the maximum tire pressure noted on the sidewall of the tire) or pinched/sliced because it is no longer encased by a tire. If the tube gets a puncture that cannot be sealed by Slime Tube Sealant (a pinch flat, a sidewall puncture or a tread area puncture larger than 1/8”) the air would simply escape from the tire until it the tire is flat.
It is possible that the tire itself may be defective. If the bead is not gripping the rim properly, when you inflate the tire, the bead slips off the rim and causes the now unsupported tube to pop. In other words, it may not be the force of the popping that blows the tire off the rim, it may be that the tire coming off the rim is what is causing the tube to pop.