A lot of people are buying the hype/rumors leading up to the Consensus conference starting today (5/22). There's also a Token Conf on May 25th where it's rumored that a "traditional company with millions of users" is going to announce a token. All of this news, plus the Metropolis release in June, and Raiden Network MVP coming soon is what we can credit to the massive increase in price. The CoinMarketCap Ethereum price includes the Korean exchanges in the ETH/USD averages, which inflates the price a bit.
I expect that there will be a sell off and correction once the news is out, even if it's good news. I think Ethereum is still undervalued though and that it will continue to climb in the long term.
Thanks! I sold a bunch (not nearly all) at the peak and balanced it with my bitcoin