Dutchman Bos, of Blanco Cycling, exploited Team Sky’s lead-out for Edvald Boasson Hagen, with Katsuha’s Kristoff surging to second and Italy’s Mateo Pelucchi (IAM Cycling) third.
Boasson Hagen faded to fourth, having hoped to improve on his two second-placed finishes.
Norway’s Kristoff, who won the first two stages, retains the overall lead, extending his lead over compatriot Boasson Hagen to 14 seconds.
Earlier in the 163km, sprinter-heavy stage, a four-man break of Lars Boom (Blanco), Tim Wellens (Lotto-Belisol), Amets Txurruka (Caja Rural) and Sven Erik Bystrom (Oster Hus-Ridley) threatened to stretch the peleton.
But the gap was soon reduced and eventually caught as the riders approached the five 8km finishing circuits towards the end.
Team Sky took the initiative but Boasson Hagen was unable to hold off the fast-finishing trio over the final few metres.