When you hear of Mike Tyson, you think of that scary, muscular, and short for his weight class boxer who became the youngest world heavyweight champ. He was knocking out dudes left and right. One has to wonder how he could hit so hard, and the reason why is the scariest aspect to him, pure boxing skill aside.
Knowing how to put your weight behind your bunches comes with basic boxing technique, and your natural physical tendencies and traits. Increase the total body weight and you have more power. The other important component is speed, or more specifically, acceleration. The reason Tyson hit so hard was his good technique and his ridiculous explosiveness at such a high body weight.