Why would a circuit breaker not trip if I accidentally shorted hot to neutral?
That noise was a wire or junction/splice somewhere vibrating and heating up. It could have also been the breaker (trying to) trip. There's a good possibility that if you turn the breaker off, it will refuse to turn back on.

At a minimum, you should replace that breaker. You should also inspect that entire length of the wiring on that circuit as you may have melted a wirenut or wire insulation somewhere.

If this were my house (and my family's life) I would call an electrician and have them inspect for damage.