Like Water for Chocolate's full title is: Like Water for Chocolate: A novel in monthly installments with recipes, romances and home remedies.
The phrase "like water for chocolate" comes from the Spanish phrase como agua para chocolate. This is a common expression in some Spanish-speaking countries, and it means that one is very angry. In some Latin American countries, such as Mexico, hot chocolate is made not with milk, but with near-boiling water instead.
An alternate interpretation of the saying "like water for chocolate" is to be like water that is hot enough to receive the chocolate (when preparing hot chocolate to drink). It is a simile for describing a state of passion or sexual arousal (i.e. 'hot and ready'). This would describe the bubbling passion Tita and Pedro have for each other throughout the book.