It sounds as if you answered your own question.
Most all nic juices that I know of are a mixture of PG and concentrated nicotine. You mix this with PG or VG plus some flavoring to make a vapable e
juice.
Here is an excerpt I pulled from
e-cigarettepedia.com which may help you understand.
Throat Hit Origins
Throat hit is the tingling sensation smokers feel at the back of the throat. It is felt when the inhaled smoke hits the throat. The term is more relevant to e-cigarette smoking because by their very nature e-cigarettes taste lighter than conventional cigarettes. Throat hit is a major concern for e-cigarette smokers because most of them converted from conventional smoking and they are used to the stronger throat hit of a burning tobacco leaf.
So, the stronger the throat hit, the better because its closer to the real thing. Lets look at some of the factors involved in producing stronger throat hit, starting from the most important.
Throat Hit Factors
#1 e-liquid Quality: Overall quality of e-liquid is cited as the most important factor in producing stronger throat hit. First time buyers of e-cigarette should research the brands that offer e-liquid that ranks high in throat hit.
#2 Nicotine Dosage in E-liquid: The dosage of nicotine can also affect throat hit. High dosage equals stronger throat hit, but again it depends on the overall quality of the e-liquid.
#3 Condition and Proper Maintenance: Life of equipment and maintenance may determine throat hit. Often uncharged batteries and clogged atomizer may cause weak throat hit; so do defective ones.
#4 Device Parts Quality: Throat hit also depends on the quality of the separate parts of the e-cigarette: atomizer, batteries, and cartridges. The model, batch, and brand play a part too.
#5 Smoking Technique: Smoking e-cigarettes takes some time to learn. It is about three times harder to draw on an e-cigarette than on a conventional cigarette. Plus getting more vapor and throat hit depends on the particular way an e-cigarette is drawn on.