It appears the fire started when the bowl's shape caused the strong sunlight to reflect off its surface and concentrate the heat to one particular point.
– A man found himself in the middle of an unexpected science experiment in Sweden after he set his bowl of grapes in the sun. Richard Walter says he was outside near his Blanda Blank stainless steel serving bowl from IKEA when he noticed his grapes were on fire. "'How is that possible?' I thought. Then I saw there was one intense point where [the sun] hit the twigs, and that's where it started." His friends wanted proof, so Walter posted a video on Facebook of a piece of paper starting to burn after he placed it in the bowl in direct sunlight. For its part, IKEA tells the Swedish tabloid Aftonbladet that it's taking the information "very seriously" and investigating how this could happen. But a statement to The Local suggests that the fiery mishap is indeed possible, with an IKEA rep saying "it has been established that many different parameters would have to converge" for fire to occur, and the risk is "very low. The round design of the bowl further contributes to a very low risk of spreading, in case of any overheated material in the bowl." Business Insider notes that no one has made any fire-related complaints on the US product page, where the bowl is described as a "great size for serving or prep cooking." (IKEA is also doing its best to preserve marital bliss.)