Why is my amplifier circuit amplifying more than I expect?

Change to the following to get a non-inverting amplifier with gain = \$1 + R_2/R_1\$

The difference is that \$R_2\$ is connected to the op amp's inverting input instead of ground.

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Please see Scott Seidman's answer for an explanation of what the incorrect circuit was doing.

Your circuit is wrong. Try to connect the lower terminal of R2 to the upper terminal of R1 (negative input of the opamp). This would give you an non-inverting amplifier with Vo = Vi * (1 + R2/R1)

For proper simulation add a ground symbol.

To add to the other answers, because the inverting terminal voltage is FIXED AT GROUND (we know this because no current, in the ideal, can enter the input terminals, thus there is zero voltage drop across the resistor R1), you have no negative feedback. Because of the lack of negative feedback, the gain of your amplifier is the open-loop gain of the op amp (maybe \$10^5\$ or so), and the output is simply determined by how close the output can get to the rail.