Tip: if you noticed, you opened up way early. You need to whip the trick around (especially for your first few times.. to get a feel for it)
Also look at where your head was looking. It was looking in front of you, and you just stopped. If you would've thrown your head more over your shoulder you would've got that last rotation in.
Your body just followed where your head was looking, and because you stopped looking over your shoulder at the 360 rotation, your body stopped rotating too.