For the U.S., legally, no notice is required. The two-week is customary; politeness, general way of doing business, etc. But if you are NOT in the U.S., please read the terms of your employment letter. In many countries, a notice period is required. If you do not serve out your notice period, you have to pay the employer your pay ... that's right. You pay money to get out of the door.
But why bother to hold on to the grudge in any case? Pity your boss who has to remain in the toxic environment (whether work or home) that's causing him/her to be the a-- that he/she is. You're getting out. Least you could do is to demonstrate superiority by being generous.