I have not been doing this very long, but it seems like when I have a good strong breakaway the string makes a snapping sound.
Is this common?
Does that happen to you guys?
This is very common
Yes it does do that to me ;D
I think that’s more due to the bind done to bring up your previous throw. Sometimes the bind loop gets a little caught somewhere in the wind and then “snaps” when it pops out as it’s thrown. The snapping noise can happen even from a normal Sleeper throw.
That makes sense, but I have not learned to bind yet. 
So you using a responsive yoyo.
response setup can cause that also, i think.
Maybe the string didnt wound up perfectly.
if the yoyo working just fine, maybe you can ignore it.
I find I get that sound when I get a really nice bind. I kinda like that sound actually, as it lets me know I got a good throw off as well
i always just figured it was because my string was too old or tight.
It is simply the way the string has wrapped itself up, whether by bind or tug.
The hardest throw will be silent, or near silent.
Energy is wasted on sound.
The energy wasted on sound, could be transferred to the spinning motion of the yo, but it wastes the energy ‘snapping’ the string, so actually your throws are less powerful, its an aural illusion.
PS: please don’t take this as I mean you have a weak throw, your throw may be still be SMOKING, what I mean is it could have been even harder, had the string not wasted energy making noise.
Hope that makes sense. Peace.