I have run into this a few times. I soak dry posole overnight, and then add it to my sweated/sauteed vegetables, add water, and stir it regularly, and it still takes over 4 hours for the kernels to pop. Is there a part of the process I am missing or doing wrong, or could I just be dealing with old posole?
Use a pressure cooker. Try for example this recipe:
where dried hominy is cooked in a pressure cooker.
The pop is a steam explosion, caused by rapid heating of the kernels' interiors.
Put the well-soaked kernels into boiling water, only enough at a time to avoid taking the pot off the boil. Add them carefully and watch them pop.
A pressure cookers heat is too gradual and heats the kernels relatively evenly.