Learn Polish: Ta impreza była zbyt nudna, żeby się rozkręcić.

The base verb kręcić means to spin or turn. The roz- ... się circumfix adds the meaning of gaining momentum, expanding, or gradually reaching high intensity. So rozkręcić się means to get going, pick up speed, or liven up, which perfectly describes a party shifting from boring to fun.

Why do we use żeby with the infinitive rozkręcić się instead of a conjugated verb?

The structure zbyt [adjective], żeby... means too [adjective] to [do something]. Because the subject of both parts is the same (the party is boring, and the party is what gets going), Polish uses the infinitive. If the subjects were different, like the party being too boring for us to stay, you'd use a conjugated past tense verb after żeby.

Is rozkręcić się perfective or imperfective?

It is perfective. The sentence focuses on the completion of the action: the party failed to cross the threshold into being a lively event. The imperfective form, rozkręcać się, would focus on the ongoing process of gradually livening up.

Can I use rozkręcić się for things other than parties?

Yes, it is widely used. You can use it for a business picking up, a movie getting interesting after a slow start, or even a person. If you are sluggish in the morning but gain energy after a coffee, you can say you need to rozkręcić się (warm up or get into gear).