At the end of movie, Dr Lecter calls Clarice at her convocation day at FBI. From which place does he call Clarice? And how did he know that Dr. Chilton was going to be there? What makes him follow Dr Chilton?
Lecter and Chilton are both in Bimini in the Bahamas which is where Hannibal calls Clarice from. It is unclear how he knew that Chilton was going to be there. But presumably, Lecter could have simply called his office and been informed that he was (going to be) on vacation in the Bahamas.
Lecter follows Chilton because of the treatment meted out to him in the latter's Baltimore asylum. He also considers Chilton to be rude and uncouth and Lecter doesn't like rude people: