Sales are exploding for this little-known soda brand with a cult following

LaCroix Sparkling Water is suddenly everywhere.

The drink has been around for more than three decades, but in the last several years it has become somewhat of a status symbol for foodies, fashion icons, and fitness gurus.

It has attracted a cult following as a result, and sales have exploded.

The neon cans have been popping up all over Instagram, filling refrigerators top-to-bottom, making appearances at weddings, and accenting countless home-made salads.

Cases of LaCroix have started filling up prime soda-aisle real estate in every major grocery store, and the drink was the subject of a New York Times magazine love letter, as well as viral news features like Buzzfeed's  "21 Things Everyone Obsessed With LaCroix Knows To Be True."

The brand's parent company, National Beverage Corp., doesn't break out individual sales for LaCroix. But according to some estimates, sales of the drink have tripled since 2009 to $175 million.

Over the same time period, National Beverage Corp.'s shares have skyrocketed more than 125%.

At a time when soda sales are declining and many major companies like Coca-Cola and Pepsi are going after the sparkling water market, how did LaCroix succeed in becoming a cult favorite?

The answer, according to one beverage industry expert, comes down to La Croix's flashy rainbow packaging and the company's decision not to invest in any traditional advertising campaigns.

"With millennials these days, it's all about authenticity and discovery, and they are suspicious of mainstream advertising messages," says Duane Stanford, the editor of industry publication Beverage Digest.

LaCroix played right into that market by sidestepping major advertising avenues like TV ads and investing instead in social media marketing and neon-colored packaging that would grab customers' attention in stores.

"Millennials see [LaCroix] as a discovery - something only they know about and their friends know about since it's not in their face all the time," Stanford said.

At the same time, LaCroix - which contains no sugar, sodium, or artificial sweeteners -has benefited from the decades-long decline in sugary drink consumption.

As soda sales have slipped, sales of sparkling water have more than of doubled over the past five years to $1.5 billion, according to data from Euromonitor cited by the Washington Post.

And LaCroix is widening its share of that market.

Coca-Cola and Pepsi both lost market share in the water segment of the beverage industry from 2010 to 2014, according to Bloomberg. Coca-Cola lost 4% of its market share while Pepsi lost 5.5%. Meanwhile, LaCroix's market share jumped 67%.