When I am reading a screenplay there is one tool that is frequently used by writers, but I did not know that there is a specific word for it until now. This word is “callback”:
It works like this: A character has a specific line in his dialog. In the end the line is repeated, but it has a different meaning and is loaded with emotion. Maybe it is a line that is said by a minor character to the main character, and in the end it is repeated by the main character himself (who has finally understood what the line really is about, emotionally). Or the line is repeated by the same character. In any case it is a very effective tool for emotionally charging an important moment of the story, especially aaround the break into the third act or in the third act.
(I learned that this is called “callback” from Screenwriting Tips. And in his Go Into the Story Blog Scott Myers also wrote about it.)