Probably sucking too hard while you are vaping. Drawing too forcefully can cause the coil heads to flood, causing excess e-liquid to accumulate in the air chamber. The excess has no place to go but into your mouth when you suck.
Try a gentler, longer draw once the air chamber is cleared. No not smoking a cigarette; a different technique is often required for vaping.
"Flooding" is a common occurrence in e-cigarettes. The definition of flooding is getting juice into the air passage of the tank. This can include any point between the mouth piece and the very bottom part that connects to the battery. Each tank has holes in that air passage, where the wicks passthrough. This is required for the device to work properly. Unfortunately, this opens up the possibility for flooding. The trick with flooding, is knowing how to avoid it. I’ll explain a little more, but a few common causes for flooding a tank include: improper filling, over filling, pulling too hard when hitting the device, and the temperature can even play a role and/or damage.
"Dry" or "burnt" hits are also a common occurrence in e-cigarettes. This happens when an inadequate quantity of e-liquid reaches the coil. This can occur from using an e-liquid which is too thick for a tank, intake holes for the e-liquid being inadequate, or using a bad wick or coil. Doing "primer puffs", which is taking a puff or two without power on, may eliminate this phenomenon.
Before I get into the explanation, let me explain how an e-cig works a little more in depth. Nearly every tank has a wick that is used to absorb the juice in the tank. This wick cuts through the air passage. Typically, the wicks look like strings hanging in the tank or is a roll of cotton, but some have smaller wicks located at the bottom of the tank and the ‘strings’ are not visible unless the tank is disassembled. Each wick has a piece of wire that wraps around it in a coil. When you activate the button on the battery, you send electricity through the wire. As the wire heats up, it vaporizes the juice that is in the wick.
Improper Filling: When filling your tank, you have to be careful not to get juice into the center tube of the tank. This center tube is the air passage. When you take a draw, air comes from the bottom of the tank, through the air passage and into your mouth. If you get juice into this passage way, your tank is flooded.
Over Filling: If you over fill a tank (specifically a top coil like the ones that come with the starter kits and gift boxes), the wicks can become over saturated and just like a rain cloud, they will leak into the air passage. Once this happens, you have a flooded tank.
Pulling Too Hard: As I mentioned the wicks absorb the juice in the tank. As you pull on the device, you cause a vacuum effect that pulls juice into the wicks. If you pull too hard, you can pull in more juice then the coil can vaporize. If this happens, the juice leaks into the air passage and you have a flooded tank.