The hypothesis is tested, ideally many times by many people
In each case, the test produces results consistent with the hypothesis

These tests form a body of evidence that serves to disprove competing hypotheses and (until some sort of contradictory evidence is found) makes the theory well-established

So you observe something, then you form a hypothesis to explain the observation, but that's not enough to be scientific. You have to actually test the hypothesis and try to explain what's happening. Merely positing a hypothesis is not good enough. A hypothesis which serves to "explain" without producing understanding is also not good enough.

In creationism / intelligent design debates there's a notion of "god of the gaps" where god is invoked to fill in a gap in knowledge, which doesn't really explain anything so much as give a label to our ignorance. The same thing happens in physics where some particle or phenomenon is posited to "explain" observations that are inconvenient / inconsistent with existing theory. Unless those hypothetical particles / phenomena can be tested and their mechanisms understood, they are just other ways of naming our ignorance.