You may not have ever consciously recognized it, but bubbles are essential to your enjoyment of beer. Without bubbles, the carbon dioxide produced by yeast during fermentation, beer just wouldn't be beer!
Don't believe me? Think about champagne. If you served champagne without bubbles to people, how do you think they would react? They probably wouldn't be that impressed, because the delicate flavor of champagne stems from those little bubbles. Plus, bubbles are visually exciting in the flute—they're part of the overall experience of drinking champagne.
Similarly, bubbles in beer are fascinating because they trigger several senses, each of which enhances the beer-drinking experience in a different way.
First, the carbonation in beer stimulates the taste buds, specifically the sour receptors. Bubbles also help to “clean” the mouth, refreshing the palate and shortening the lingering aftertaste that is sometimes present in very bitter beers.
A second area triggered by carbonation is one that you've probably experienced when eating buffalo wings or spicy Thai cuisine: the trigeminal nerve. In short, the trigeminal nerve is partly responsible for detecting pain, like the pain caused by the capsaicin in hot peppers. Chugging a highly carbonated drink causes something akin to pain, as the trigeminal nerve responds to the intrusion of carbon dioxide.
A third piece of the sensory puzzle affected by carbonation is our sense of a drink's temperature. Chances are, if you were to drink sparkling water and still water, both at the same temperature, the sparkling water would seem more refreshing. This is the magic of bubbles. It's a physiological anomaly, but the carbonation in beer and other drinks affects how we perceive their temperature, which in turn makes a drink seem more or less refreshing. More scientific experimentation is necessary before we can fully understand this relationship.
Finally, bubbles add to one more part of the sensory experience of drinking a beverage. Depending on the nature of the drink (beer, soda, or sparkling wine), the bubbles can burst in your mouth, your throat, or your stomach. This is because bubbles are pockets of gas within a liquid and therefore are influenced by the composition of that liquid.
Since beer is much richer in proteins than soda or wine, beer bubbles tend to be much finer and much more stable—they're literally protected by an invisible protein “armor.” Generally, beer bubbles persist through the mouth and throat and don't burst until they reach the stomach. This may contribute to the feeling of bloating that some people associate with drinking beer. With many tiny bubbles exploding in your stomach, you feel full quicker, compared to when the bubbles pop in your mouth, leaving you less full, with merely a pleasant tingling sensation on your tongue.
Different beer styles will display different bubble dynamics, creating unique sensations. No matter the style, though, bubbles are a fascinating aspect of drinking beer. Think about that the next time you crack open a craft beer and take your first sip.