“Mulled wine” (ponche) is a type of drink that is often heated to which spices are added (calentar con species). If you have been to Madera, you may have tasted “mulled wine”.
To “mull over” reflexionar sobre) is a phrasal verb that means to contemplate or reflect over something. In the speaking parts of the Cambridge First and Advanced exams, a useful phrase is “I need 2 seconds to mull over the question”, that is, to give yourself sometime to think about the topic.
So, perhaps you pour yourself a glass of mulled wine and then mull over the purpose of life.