Stickiness is music is when the mind can predict what comes next without ever actually hearing what comes next before.
For one, sticky songs (hooks) can also be unpredictable/unexpected. E.g. you're not able to predict what will follow from the first part you hear, but it sticks to your mind after you do hear it in full.
Second, there are hooks where you DO hear "what comes next before" (e.g. they are based on repeatition of notes in the core hook) and that doesn't stop them being sticky.