Plosive

Say the word popular into your hand and you can feel it. That puff of air is what a plosive is, and a microphone close enough to catch a warm voice is close enough to catch the blast. On the recording it lands as a dull thud under the word. No amount of volume riding will hide it. Two fixes matter: move the mic off-axis so the air passes across it instead of into it, and put a pop filter in the path. A high-pass filter in post tidies up what is left, though moving the mic costs nothing and does most of the work.