The Squib round doesn't cause the explosion...its that bullet from the short-powder-load-round being stuck in the barrel
when you load & fire the Next Round that causes a Kaboom! Much like having mud stuck in the end of a barrel...very bad.
If you hear a funny POW when you fire, Always stop and check your weapon...chances are high something is very wrong.
Happens to .22LR's a lot, especially with Remington Golden Bullet ammo.
Its the reason I always carry a 3-piece cleaning rod to the range, along with a full cleaning kit...
never know what'll happen any particular day...best to be prepared