Question

What do the rapid changes or “breaks” in a titration curve represent?

Answer 1

those "rapid breaks" in pH are the neutralization of acid/bases

i.e.

initially you have plenty of acid, then you start neutralization, little by little H+ ions are reduced

eeventually, neutralization is achieved, but this is pertty exact

that is

to a certain volume (very very prceise)

it is almost impossible to achive it, th emost normal thing in the lab is to have a little bit excess of base

this will change from acidic to basic, and this is the "break" you are talking about