Program won't crash when it should

(GCC C)
I ran a pointer over each member of an integer array, storing one character of input in each cell.

The program seems to consistently crash when I try to store X+3 or more characters, where X is the size of the array, but if I do not exceed X+2 it will not crash.

Why does it crashes exactly at the point it does, but not for X+1 or X+2?

Take a look at this.

#include <stdio.h>
#include <stdlib.h>

void g() {
    puts("Hello, World!");
    exit(0);
}

void f() {
    int stack[1];
    /* stack[0] is local data.
     * stack[1] contains ebp.
     * stack[2] contains the return address. */
    stack[2] = g;
}

int main(void) {
    f();
}