BK-
Do I take it you are moving to Houston (AKA Humidity, TX)? If so, welcome to my world. What part of Houston? Hope you don't have any allergies; if you don't, you will.
BTW, the main reason for slab construction in Houston has nothing to do with the water table. Since the ground never freezes in Houston, there is no need to go down into the ground to get the foundation below the freeze line, nor is there any bedrock to build on, and builders build as cheaply as they can, so slabs it is. Not a problem with a properly engineered and poured slab. Unfortunately, much of the soil around Houston is "gumbo" which expands and contracts quite a bit with changes in water content and has resulted in many a cracked slab (again due to the cheap build quality of many slabs). Slab repair is big business here. I have never heard of a pool "popping out of the ground", though. Similar to slab construction, an improperly engineered pool can crack as a result of soil expansion and contraction.
In any case, it is wise to avoid the pits as you have observed they would be prime mosquito breeding grounds and we don't need any more of those in Houston.