Moving jobs is the best way to get a large pay increase, especially if you're underpaid in your current job. Once you tell them how much you currently make, you've screwed yourself. This is a negotiating tactic used by employers to know how much they'll set as their upper bound for pay.

Your employer may have strict pay bounds set, but a lot of places don't. The pay can vary highly between candidates, especially if the candidates are weak negotiators. If you disclose your current salary, you're a weak negotiator, but employers put a lot of pressure on you to disclose it. I tend to tell employers that I'm not allowed to disclose my salary, which ends that part of the conversation, but most people don't know to do this.

This law benefits you just as much as it does women.