You might be referring to subatomic particles "popping" into existence?
Just because we don't know why, or where from, doesn't mean that your assertion is correct--it's quite INcorrect. There is a cause.
We just haven't been able to determine their cause for existence, but we know that everything has a cause, unless you are subscribing to some form of "magic."
So I disagree with your reasoning. It makes the assumption there is NO cause, and in time, our science will prove you wrong.
No. Radioactive decay is spontaneous and uncaused, and by that I do not mean that the cause is currently unknown - I mean that it is provably the case that decay is uncaused. If there were a proximate cause for the instantaneous decay of an atom, even an unknown cause, the experimental results would be different from what they are.
Causality is simply not a universal rule, necessary always and everywhere. Hence, any argument that relies on causality as a hard and fast rule, as the kalam argument does, is plainly dead on arrival.