A good foundation is key to a good house. A poorly constructed foundation will cause problems with the entire structure. A well constructed foundation can be compromised by expansive soils supporting it. This is especially common in North Texas. Keeping the foundation from getting too wet or too dry is key to reducing movement. This can be done by properly draining the yard around the house and using a sprinkler system to add moisture during a dry spell.
Common signs of foundation movement are diagonal cracks in exterior brick walls, interior floors, and interior sheetrock walls. The more movement the foundation has, the larger and more numerous the cracks will be. Cracks at the corners of windows and doors are especially common. Doors that do not open and close properly, particularly on the interior of the house, are a strong indication of movement.
Corner pops are cracks or missing sections of concrete on the exterior corners of a foundation that is holding up a brick wall. This occurs because the brick is sitting on the concrete foundation and the brick wall heats and expands at a different rate than the foundation supporting it. This pushes the foundation corner and can crack the foundation corner. It sometimes completely pushes the corner off the foundation. If the corner section is not broken off and continues to support the brick wall above, it does not usually require repair. If the section is completely missing, then the brick wall is no longer being supported and requires repair. Corner pops are not necessarily a result of foundation movement. A house with a perfectly sound foundation can have corner pops. Below are photos. The first one is of an intact corner pop, indicated by a diagonal crack. The second is showing a missing section that requires repair