A student performs four separate lab procedures at \(25^\circ\text{C}\) and atmospheric pressure, recording the initial conditions and final observations in the table below.

Procedure	Initial system	Manipulation	Final observation
1	\(10\text{ mL}\) of colorless \(\text{KI(aq)}\)	Added \(10\text{ mL}\) of colorless \(\text{Pb(NO}_3)_2\text{(aq)}\)	Immediate formation of a bright yellow solid
2	\(50\text{ mL}\) of colorless \(\text{H}_2\text{O(l)}\)	Added \(2.0\text{ g}\) of white \(\text{C}_{12}\text{H}_{22}\text{O}_{11}\text{(s)}\) with stirring	Solid disappears to form a clear, colorless liquid
3	\(10\text{ mL}\) of dark blue \(\text{CuSO}_4\text{(aq)}\)	Added \(40\text{ mL}\) of colorless \(\text{H}_2\text{O(l)}\) with stirring	Mixture becomes a uniform pale blue liquid
4	\(25\text{ mL}\) of colorless \(\text{H}_2\text{O(l)}\)	Heated from \(25^\circ\text{C}\) to \(100^\circ\text{C}\)	Bubbles form and liquid vaporizes as steam

Based on the observations recorded in the table, which procedure provides the best evidence that a chemical reaction occurred, and why?