In the case of our bubble, it houses a Multiverse.
The laws of reality can differ greatly from bubble to bubble as it all depends on the rules set forth by its version of The First God. If someone can create fireballs and then travels to a different bubbleverse, then they may suddenly find themselves capable of manipulating water instead.
Travel between bubbleverses is near impossible and has (as far as we know) only ever been successfully demonstrated once, with the voyage of the Gascoin race.
There is no way to know the number of Bubbleverses in existence, but it is theorized to be so unbelievably huge it might as well be infinite.