AI (not) managing cities

In my current campaign I have taken a large number of cities and have the AI managing the taxation (by the overall diplomacy screen not by have any of the boxes ticked on the individual city screen). What I have noticed is that originally the AI would keep the taxation level as high as possible without causing riots but then after a number of turns it would suddenly switch and reduce all the taxation levels to low causing a population explosion (without my having done anything to precipitate this).

Has this happened with anyone else? Any suggestions?

Local elections? *shrugs*

When you have built most of the available buildings in a settlement, the AI governor will attempt to raise the population to the next settlement level (so that you can get more advanced buildings there). You can avoid this by setting the priority to financial. Similarly, you can overrule the normal mode of getting max money by setting priority to growth, which always sets taxes to the lowest.