If you like to see it from a mathematical perspective:

DOL = \frac { \% Change \ In \ Operating \ Income}{\%Change \ In \ Units \ sold} = \frac {(SP - VC) \times Q_0}{(SP - VC) \times Q_0 - FC}

Contribution \ margin_0 = (SP - VC)

Operating \ income_0 = (SP - VC) \times Q_0 - FC

If **contribution margin increases by 50%**, then:

Contribution \ margin_1 = 1.5 \times (SP - VC)

Operating \ Income_1 = 1.5 \times (SP - VC) \times Q_0 - FC

So:

\% Change \ in \ Operating \ Income = \frac {Operating \ Income_1 - Operating \ Income_0}{Operating \ Income_0}

\% Change \ in \ Operating \ Income = \frac {[1.5 \times (SP - VC) \times Q_0 - FC] - [(SP - VC) \times Q_0 - FC]}{(SP - VC) \times Q_0 - FC}

\% Change \ in \ Operating \ Income = \frac {(1.5 \times Q_0 - Q_0) (SP - VC)}{(SP - VC) \times Q_0 - FC}

\% Change \ in \ Operating \ Income = \frac {(0.5Q_0) (SP - VC)}{(SP - VC) \times Q_0 - FC}

\% Change \ in \ Operating \ Income = 0.5 \times \frac { (SP - VC) Q_0}{(SP - VC) \times Q_0 - FC}

\% Change \ in \ Operating \ Income = 0.5 \times DOL = 0.5 \times 2 = 100\%