Is there a secret to get more popcorn kernels to pop?

The only trick is to apply exactly the correct amount of heat for the correct length of time, and each batch is variable, so there is no fixed answer.

Some people say refrigerating before cooking helps. I don’t know if that’s true.

It certainly helps to shake it a lot. Kernels can get trapped away from the heat or heat unevenly otherwise.

I find a brand I like – then find the best heat/time ratio – and record it. I microwave – so I have a little note on it reminding me that brand x requires 2.32 minutes for optimal popping.

I have refrigerated mine on accident and it always ended up with the bag having burned popcorn in it and a scorch mark on the bottom of the bag.

I find that having the oil sufficiently hot does the trick. For my popcorn popper, that means no less than 5 minutes of pre-heating. However, my guess is that on the stove, the time may be less. As @6rant6 mentioned, keep it moving!

Moisture inside the kernel is important to the pop; perhaps the corn was old.

BarnacleBill is right. Using a good brand that is fresh really makes a difference.

I find that having the oil hot before adding the kernels helps, shaking constantly for even heating, and using just enough kernels for one layer in the bottom of the pot.