BSOD when trying to shut down the computer

Okay, I'll just RMA it.

When I purchase ram, do I have to purchase "Kits" that come in packs of 4?
Or can I buy the packs of 2, and just purchase 2 of them to equal 4?
Meaning, if 1 pack = 8gb [4*2], and I want 16, can I just purchase the same set of packs?
Also, I did thoroughly read through the info. you provided, however, just to clarify a bit more,
If I have a set of CMZ8GX3M2A1600C9B, which I purchased months ago, and I purchase another set of CMZ8GX3M2A1600C9B, will this still mean i'm prone to instability and bsods?
Because I know these Rams come in sets of 4 as well.

Not saying you'll be prone to them if you buy them at different times, just that it is a possibility. It is better to buy a pack of 4 if it is available, but two sets of 2 usually work. As I said, I have seen times when they didn't. I have even seen two "identical" packs bought at the same time end up being slightly different, though that is really rare.

And if you get two packs that are not actually identical, you can RMA them and ask to get two packs that are identical and companies are very good about doing so the second time around.

Just to clarify, that means that if I have a cmz16gx3m4a1600c9b, I can get another set of cmz16gx3m4a1600c9b 8gb [4*2] ram chips? Just as long as they're the same model as the ones I'm about to RMA?
Or am I not advised to use them because I didn't buy the same pack of ram chips together months before I bought my first set of ram chips?

Yes, you can get the same model. It will likely work with your current set if the current set and the new set are both the same model.