dilate
/ˈdī-ˌlāt/
verb
to become enlarged or widened; also : to display or become affected by expansion or widening of a body part
to become expanded in extent
to comment at length : discourse —usually used with on or upon
Kim's eyes dilated while the outdoor stadium rocked in celebration.
Understandably, a tendency to philosophize dilated with old age.
phrasal verb
to talk about (a subject) for a long time
We spent a long evening listening to him dilate on the need for tax relief.