Question

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

Answer 1

Because " taxation without representation." They didn't want to be taxed for every single thing they had to buy from Europe.

Answer 2

The correct answer to this open question is the following.

The colonists were so angry with the heavy taxation imposed by the British crown that they boarded ships containing tea in Boston and other colonies. Specifically, the Boston Tea Party was the political protest of December 16, 1773, in Boston, Massachusetts. Colonists tired of "taxation without representation" threw 342 chests of tea into the Boston harbor. The tea belonged to the British East India Company. This kind of taxation, as well as the Stamp Act or the Sugar Act, were causes of the Revolutionary War that was fought to gain independence from Britain.