Most of the times, when some people talk about "events without explanation", those events are actually "highly unlikely and with low probability of ocurrence".
Possibility and probability are two different things.
Most "unlikely" events are possible (or explainable under the current scientific paradigm).
I suggest to not understimate the power probabilities, big numbers and statistics. There are billions of humans beings, so there are chances for unlikely events to happen more often than not.
Please, notice the use of the word "most".
I doubt scientific knowledge is near to be complete.