The 24-year-old, who began the European Ladies Tour season with victory in Australia, goes into the final day seven under par, two ahead of Finns Minea Blomqvist and Ursula Wikstrom.
Boeljon, joint halfway leader with Wikstrom, eagled the fourth in a front nine 33 and then had a hat-trick of birdies from the 11th for the second day running.
Instead of adding a fourth in a row again, however, she double-bogeyed the 14th and saw her lead cut in half.
Blomqvist's fourth birdie of the day on the 15th made the gap only one, but she then bogeyed two holes later and had to settle for a three under 70.
Wikstrom came back into the picture when birdies at the 12th and 17th gave her a 71.
Big move of the day came from Spaniard Carlota Ciganda. She fired a professional women's course record of 66 and will resume three behind in fourth place.
The 21-year-old Tour rookie from Pamplona, winner of the Spanish Championship two weeks ago, mixed nine birdies with two bogeys and said: "It was one of those days when everything went right.
"I feel ready (to win again), but I know it's not easy because I know there are many great players out there."
Teenage English amateur Charley Hull, playing her first Tour event, slipped four places to eighth with a level par 73.
Boeljon, whose eagle came with a three-wood to 10 feet, said: "It was a shame about the 14th, but I think overall four under on this golf course is good.
"I don't think with any score you could be comfortable going into the last round. There's a lot of golf left and it's a tough course."