[coldtea]

Not necessarily. That's familiarity. But a familiar piece might not be sticky at all, just boring.

[panic]

Exactly. Otherwise the same note played over and over at an even tempo would be "sticky" (which is nonsense).

[7Z7]

"..without ever actually hearing what comes next before."

[coldtea]

Still not relevant. There are several studies on the impact of music and the role of familiarity, structure, anticipation and such. There's even one decicated to the use of such musical notions in the music of the Beatles ( http://www.amazon.com/Songwriting-Secrets-Beatles-Dominic-Pe... ).

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.

[7Z7]

How can you be familiar with something you've never heard before?

[coldtea]

Very easily. If it follows a structure (melodic, harmonic, rhythmic, etc) that's the same with other things you've heard before.