I am not sure, but I think that memes boomed bigtime with the reinvention of GIFs and GIF services as such. Of course with the internet and static memes and their spreading through social media it was on the rise, but the GIF really punched it through.
But what does a meme really mean? Actually it is a term from the last century and that means last millennium. Term coined by Richard Dawkins in his book The Selfish Gene. And no, it is not a romance about a guy named Gene who was selfish. It focuses on genes as a basic unit as opposed to organism-centric or group-centric views, but I am sure you can search the details or even read the book if you want to get deeper into some British view on ethology and evolutionary biology. Ok, to get back on track in 1976 in The Selfish Gene the term meme was born!
Now the definition of a meme is not “a funny pic with a catchy line” a definition of a meme is basically a cultural gene. In other terms what is gene to biology – a meme is to culture. Similarly the successful (stronger) memes tend to survive and replicate in culture and the poorer memes die off. They are spread by non-genetic means by humans, by imitating (retelling, drawing, showing, etc.). Maybe now it tends to be more obvious why today it got also the more simplistic (but still sticking to its origin) meaning of the “funny pic with a catchy line” – which is a mean of a self-replicating cultural information.
Regardless of whether Dawkins is right and scientific in his book or (as some) argued it is pure nonsense and pseudoscience, interestingly the beauty of today’s memes on the internet is that they actually fit into the theory and spread as memes and many of them tend to survive and replicate quite fast… hmmmm.