I believe Hamlet went crazy somewhere in the begining of the play. He starts talking to himself and acting all out of the ordinary. Becuase he knows what happened to his dad and who did it he feels this need to kill the king and it's driving him crazy that his mom is married to him, that she acts like his father's death didn't really matter, and that he knows who killed his dad and he isn't dead himself.
Hamlets "transformation" relates to revenge, insanity, and broken families.
Revenge: He is plotting to kill the king because he know he killed his father and how he did it.
Insanity: Him knowing all of this information and not really being able to tell anybody or act upon it right away is to much for him and it's building up inside and making him go crazy.
Broken Families: His mom married his uncle as soon as his father was killed and nobody is really acknowledging the fact that the real king is dead. And because his mom married his uncle Hamlet is starting to act distant towards his mom.
"Why, what an ass am I! This most brave,
That I, the son of a dear father murdered,
Prompted to my revenge by heaven and hell,
Must, like a whore, unpack my heart with words
And fall a-cursing like a very drab,"
(2.2.611-615)
