MacBook Pro Shutting Down Unexpectedly

I am experiencing a random and unpredictable issue with my MacBook Pro. I will be using it per normal, and for no reason (or at least no predictable action), the computer will lock for 10-15 seconds, and then shut off completely. When I reboot it, there is no error message stating that it shut down because of a problem, or crashed in any way.

If it locks and I wish to expedite the process of shutting it down by holding the power button until it turns off, then I get an error message on boot-up, saying I shut the computer down due to a problem, and would I like to reopen any programs that were operating at the time.

If I knew where to look in the logs, it might reveal whatever is causing the lock down and shut down. Regardless, I can point to no predictable action which would cause the issue.

MacBook Pro (Retina, 15-inch, Late 2013)

Processor 2.3 GHz Intel Core i7

Memory 16GB 1600 MHz DDR 3

Graphics NVIDIA GeForce GT 750M 2048MB

Intel Iris Pro 1536MB

macOS Sierra, Version 10.12.6

Thank you.