I hear loud popping or thumps often from a wall that is in my Florida room addition-it is an outside wall and there has been some wicking from below-from sliding door tracks. The floor is a cement slab-it was an addition built on the house(Miami, 1980s) but I also hear the same cracking sound from a wall in the house (remodeled but built in 1956)-no where near the first wall I spoke about above and this is also an outside wall but there is no water leakage in that area so totally different scenario but the same noise. Though somewhat mechanical, I cannot figure this out and have heard it for years...

Noises of this nature are typically expansion and contraction noises caused by heating and cooling the structure. This may be particularly noticeable on south or west walls during the fall when the sun sets enough to really heat load the wall. If you don't see settlement cracks on the walls or door and window casings, it is something you may have to put up with. Some evergreen shrubery along the south and west walls may help keep the heat off. .

Thank you for your answer-I did think of the contracting/expanding but It is more frequent than years ago-both walls face east- one to the north, one to the south-we are in Miami, do have heavy folliage on the outside of both walls and both walls are cement block and drywall-both are in proximity to either a window or door-no settlement cracks noted and I do not hear it anywhere else in the fairly large ranch house... I am convinced I will have to live with it but it is very strange... Thanks , again!

I'd still go with temp related noises. Over long periods, nails loosen and even a little movement causes noises. Do you by any chance have a metal roof?