Bitcoin’s price continues to rise, and it’s starting to make the cryptocurrency world a little nervous.

These past few months have seen the crypto’s price rise nearly 12% YoY, according to data collected by Coindesk, which has in turn swept up the price of other cryptocurrencies like ether and Ripple’s XRP.

Holders of cryptocurrency are mainly concerned over what’s going to happen afterwards—when this so-called “bubble” finally bursts.

There are multiple causes for the price hikes, according to a cryptocurrency trader Jacob Eliosoff, who runs an investment fund specializing in Bitcoin, including the growth of the “token sale/Initial Coin Offering, and increased interest from investors in countries such as Japan and Korea.

Eliosoff told Bank Innovation:

…Factor Number 1 in the general price rise is just another of crypto’s periodic bubble: see Nov 2013, March 2013, July 2011.  Lots of coins which patently have no plausible long-term use case or value–the classic example is Dogecoin, an obsolete joke–have set new highs during this frenzy – a bad sign.

The rise of these cryptocurrencies has been “widely discussed for the past three months or so,” according to Eliosoff—months, which have seen bitcoin coming near a new all-time high of $3,000. The cryptocurrency is trading at around $2,800 at the time of this reporting, according to data from Coindesk, while ether is trading at about $260.

The rise of ether is of particular note during this bubble, as investor and enterprise interest in the technology continues to rise, a feeling echoed by most in the cryptocurrency world even as concerns over the near future increase. “Fundamentally this remains a promising technology, and entrants like Ethereum are genuine innovations which may have a lasting impact,” Eliosoff said. “But for now, a crash is coming, even if no one can say how many more times these coins will double before it comes.