This wasn't one death, but 21 deaths -- all from the same bizarre cause. On a warm day in January 1919 in Boston, a large tank containing about 2.5 million gallons of molasses exploded in a neighborhood in the city's North End. The tank was 50 feet high (15.2 meters), had a diameter of 90 feet (27.4 meters) and was situated on the waterfront in an area populated at the time largely by Italian immigrants. Nobody is sure what caused the massive explosion that sent shrapnel flying as far as 200 feet (61 meters) [source: wired.com].
Some of the deaths are attributed to the force of the blast itself, and it's impossible to say now exactly how many perished in the aftermath. But we do know that the explosion caused a wall of molasses that was reportedly 25 feet (7.6 meters) high to flow into the neighborhood at an estimated 35 miles per hour (56.3 kph) [source: wired.com]. The sticky wave knocked people over and sucked them in, causing them to drown in the thick, brown liquid.
It took months to clean the mess up and more than 100 lawsuits were settled for almost $1 million six years after the accident occurred [source: wired.com]. That's more than $12 million in 2009. Residents of the unlucky neighborhood claim they can still smell the molasses on hot summer days.