If I was a betting man I would say most of that dry hit taste is
juice that is burning rather than vaporizing.
And that is because there just isn't enough
juice at the coil to keep the temperature from elevating too much and too rapidly.
If your
device is using silicon wicking material that stuff does not burn, so it isn't that.
But I suppose there could be some sort of taste coming from the overheated coil wire as well.