If there was ever truly nothing, then by definition that "nothing" cannot have contained anything in it that would predetermine what would happen in any way at all. Therefore, anything could then happen. Because there is nothing to stop it from happening.
The only way to have no potential for anything to happen is to have something preventing that potential (in other words, some power deciding what potentials will or won't exist), but "something" is not (by definition) nothing. Therefore, it is logically impossible to have a "nothing" that lacks any potential, because such a lack would entail the presence of something preventing or limiting that potential.
You are left with a Catch-22: either you have nothing except some actual thing that limits all potential (which is not absolutely nothing, because something then actually exists, and this begs the question of where that limiting "something" came from and what gave it its power), or you have nothing except the potential for anything. The latter is as close to absolutely nothing that could ever logically be. For a potential to be is closer to nothing than actually being. In other words, if nothing exists but the potential to exist, then that must be closer to nothing than having some actual thing exist that limits what can potentially exist. And if the only logically possible versions of "nothing" are nothing with no actual thing in it (in which only the potential to exist exists) and nothing with some actual thing in it (which limits what has the potential to exist), clearly the former is closer to nothing, in fact as close to absolutely nothing as it is logically possible to be.
This is confirmed by the observation that, unlike a nothing that has some actual thing added on to it that determines what will and what won't have the potential to exist (which added thing begs an explanation of why it exists and has that power), the potential that arises from absolutely nothing begs no explanation. For the "absence" of any power limiting what can potentially exist is exactly what "nothing" is, hence positing "absolutely nothing exists" already explains the presence of all unpredictable potential. Hence to have such an unpredictable potential, no other thing need exist except "nothing." Nothingness therefore explains the presence of unbounded potential, leaving nothing more to explain. It is therefore self-explanatory.