Why were colonist so angry that they boarded ships containing tea in Boston and other colonies?

The colonist were so angry that they started something called the "Boston Tea Party", because the tea act was announced. History lesson! The Tea Act was an act made to tax the colonies to show that the British were in control. The colonist believed, since they had no vote in the British government, that this was taxation without representation. When the colonist protested, and refused to buy tea, the British blocked the Boston Harbor and said no one may leave until the tea was unloaded. This made the colonist mad, so they "unloaded the tea" by dumping it into the harbor. That started another act called the coercive acts or the unforgivable acts, but that's a lesson for another time!