Also putting sugar in water raises the boiling point a few degrees. It also lowers the freezing point, hence put salt in water in your ice cream maker ice bath.
True, but she did not add the sugar to the kettle, but to the already boiled water in the bucket. That will not raise its temperature. The energy going into dissolving the sugar will actually (very slightly) lower the solution’s temperature - but in the end it was still hot enough for the devastating result.