A reassessment year is usually the biggest driver of a large jump, because your home's assessed value can change substantially even if the mill rate itself barely moves, and the taxable portion is 80 percent of that new assessed value under provincial rules.
In a non-reassessment year, the swing is generally smaller and driven mainly by the mill rate the City of Saskatoon sets to cover its budget, which is public and debated before council each year rather than set behind closed doors.
If a jump looks disconnected from anything that actually changed about your property, checking the notice for a factual error is the first step before assuming the number is correct. Get your hand-reviewed valuation from Joel Dyck.