One of the regular duties growing up was the making of beans and tortillas. It was my job to hang around and help Grandma with this three times a week.
Tortillas were done with a mix, though she had a recipe handy if we ran out.
Beans were bought dry in bulk, about 5 pounds at a time. She'd take two cups full, dump them in the deepfryer/slowcooker filled with water, throw in half an onion, some salt, and set it to (memory says)400 degrees. The stuff would boil for about and hour and a half, and she'd toss in about a teaspoon of Caldo de sabor de Pollo. Half an hour later the beans were done. Perfect. No spots, no skin peeling off (well, maybe there was) and nothing crunchy.
I've been trying on my own for the last 20 years and it's been a pain. I tried the little one quart crockpots. I've tried big crockpots. I've tried stovetops. Nothing. I had moderate success soaking the beans overnight and discarding the soak water (helps with gas, too).
My sister sent me this link, which has the little trick of boiling then soaking. I put some beans and water in the microwave for 5 minutes, then let it sit for an hour. That helped some.
Nowadays I just use a regular nonstick saucepan with a reasonably tight lid. I soak a cup of beans for at least 8 hours in two cups of water. I rinse the beans and then put them in the pot with 2 or 3 cups of water, depending on the relative humidity. I put in a half teaspoon of salt, a wedge of onion, and bring it to a rolling boil.
Once it's boiling, I reduce the heat to low and put the lid on. This lets it boil again, but not lose the water as fast. About an hour and a half later, I put in the chicken bouillion, and simmer for another half hour.
There's no magic to putting the salt and bouillion in at different times, it's just habit. I've noticed that the beans are saltier if I put the table salt in late, but that's about it.